Medical appliance with centering balloon

ABSTRACT

The balloon catheter comprises a catheter tube surrounded distally by an elongated inflatable balloon. Throughout the catheter tube is a longitudinal lumen for positioning a radioactive radiation emitter within the balloon. The catheter comprises a second lumen for directing inflation fluid into the balloon. Belt means creating a waist are mounted on the balloon to squeeze it down to nearly the diameter of the catheter thereby leaving a small passage for the inflation fluid. The belt means divide the balloon into sections to assure a close center fit of the catheter within the balloon.

BACKGROUND OF THE INVENTION

This invention relates to a medical appliance for the treatment of aportion of body vessel by ionizing radiation, comprising a catheter, aninflatable elongated balloon distally surrounding the catheter, andlumen means longitudinally extending through the catheter forpositioning a radioactive radiation emitter within the balloon.

U.S. Pat. No. 5,213,561 describes a device for preventing restenosisafter angioplasty comprising, among various embodiments, a catheterhaving a balloon at its distal end and a center core or tube in which aconventional guidewire is receivable. Particles or crystals ofradioactive material are embedded in or mounted on the tube inside theballoon and a retractable shielding sleeve is slidable along the tube tocover the radioactive source, blocking exposure to radiation until it isshifted away. Such a structure is said to allow radiation of a vascularstructure immediately following completion of angioplasty, withoutseparately inserting a radiation source.

Standard dilatation balloons are not well suited to transport and totake up radioactive radiating sources because the center core orguidewire lumen tends to warp on the stretch inside the balloon, therebyforming an undulated line. The radioactive radiation source, however,has to be centered as exactly as possible inside the vessel in order toavoid the vessel wall being burned.

The document DE-9102312.2 describes balloon catheters for performingangioplasty procedures followed by radioactive irradiation to preventrestenosis. In a first embodiment, there is provided a catheter closedat its distal end and bearing a dilatation balloon which can be inflatedby a fluid medium supplied via a lumen extending longitudinally of thecatheter; a radioactive seed affixed to the end of a guidewire may beinserted into the catheter lumen to be brought into the site ofangioplasty while the balloon is inflated; according to a variant, thelumen of the catheter may be separated in two parallel channels by alongitudinally extending intermediate wall, one of the channels beingfor insertion of the fluid for inflating the balloon and the other forinsertion of a guidewire having the radioactive seed affixed at its end.In a second embodiment, the catheter comprises an additional channelcentered in the catheter lumen by means of two longitudinally extendingintermediate walls; the catheter lumen is thus divided into threechannels, of which the central channel is for insertion of a radioactivepin affixed at the end of a guidewire and the lateral channels forballoon inflation and for supplying drugs into the blood vessel,respectively. In a third embodiment, the catheter bears two balloons ata distance from one another and which can be inflated separately; thecatheter also comprises a central channel centered in the catheter lumenby means of four longitudinally extending walls defining four channelssurrounding the central channel; two of the surrounding channels arerespectively opening into the balloons for inflation thereof, and thetwo other surrounding channels are respectively opening between the twoballoons to allow injection of drugs in the vessel area comprisedbetween the two balloons; the document indicates that a radioactive seedaffixed to the distal end of a guidewire may be placed in the lowest ofthe surrounding channels; the document also indicates that theradioactive source may be placed in the central channel, furtheroutlining that, as with the second embodiment, the radioactive sourcemay even be driven out of the catheter to directly irradiate the vessel.Apart from the fact that this document does not consider any particularcentering of the radioactive source in the body vessel, its variousconfigurations do not allow such a centering.

In the first embodiment of this document DE-9102312.2 no measures aredescribed which would ensure circumferentially uniform radiation impacton the vessel wall and the radial position of the irradiation source ismerely determined by gravity, whereby warping of the catheter lumen uponinflation of the balloon will add to the unevenness of radiationdistribution in the vessel. In the second embodiment, any warping uponinflation of the balloon will be fully uncontrollable because of thedifferent reactions of the main channel, additional channel andlongitudinal walls of the catheter to the stresses resulting from thestretch inside the balloon; this of course makes it impossible to knowwhere and how the radioactive radiation will be distributed in thevessel. In the third embodiment, the situation shows the same drawbacksas for the second embodiment, with some more uncertainty resulting fromthe additional channels.

The document DE-3620123-A1 discloses an apparatus for measuring andirradiating body cavities which permits the placing and positioning of alight conductor at the center of a cavity in order to achievehomogeneous lighting thereof via a dispersing agent.

To this effect, a light conductor is located in a tubular cathetersurrounded by two optically transparent centering flexible balloons at adistance from each other and which are inflated by a dispersing agent inorder to have them rest against the wall of the body cavity. The portionof the catheter which is located between the balloons is stiffer thanthe rest of the catheter to avoid modification of the distance betweenthe two balloons, for instance due to curving of the catheter. Thesystem is said to be usable for a blood vessel, and the two balloons areocclusion balloons. Occlusion balloons have to be resilient to safelyfulfill their task in a vessel of unknown exact shape and size. Becauseof this resiliency, occlusion balloons can not be used simultaneously asdilatation balloons. Resilient balloons would overstretch the vesselwall when used with the higher pressures that are required for asuccessful angioplasty. Of course the doctor has control over theinflation pressure with resilient balloons same as with dilatationballoons, but this is not sufficient for safe angioplasty. With aresilient balloon the doctor has no control over the inflated diameteror over the shape to which the balloon is inflated. Of course, with thisapparatus the source could be centered if the balloons are closetogether, but the additional weldings of two balloons close togethermake the catheter more complicated and expensive. Furthermore, the addedweldings reduce the flexibility of the catheter which is necessary tomaneuver it through tortuous vessels and to use it in tortuous vessels.

The purpose of this invention is to improve the conditions ofradioactive radiation treatment of body vessels by proposing a medicalappliance with inflatable balloon for a vessel wall radiation which isuniform around the vessel, an appliance that is highly versatile, simpleto manufacture and easy to use.

SUMMARY OF THE INVENTION

In the present invention, a waist centers the lumen containing theradioactive radiation emitter inside the body vessel at least at thelocation thereof and substantially eliminates any undulated shape whichmay be taken by the catheter or lumen containing the radioactiveradiation emitter. The stretch occurring upon inflation of the balloontherefore does not affect the positioning of the radioactive radiationemitter within the body vessel. And the appliance may retain a goodflexibility allowing its maneuver and use in tortuous and/or narrowvessels.

Specifically, it becomes possible to improve dosage control of theradioactive radiation with regard to the distance between radioactivesource and vessel wall, whereby overdosage because of too narrowdistance and underdosage because of too wide distance to the vessel wallis avoided, and the impact of radiation on the vessel wall isessentially uniform.

The waist may be created by belt means which may be regularly orirregularly spaced from one another over the length of the balloon inorder to match any structural configuration and warping tendency of thecatheter and balloon assembly.

For inexpensive fitting of existing balloon catheters, the belt meansmay be made of surgical thread, possibly surgical thread tied with aknot.

To modulate the centering of the catheter within the balloon, the beltmeans may be made of molded rings, the length and thickness of whichwill be chosen as a function of the strength needed to counteract thewarping tendency of the catheter.

For safety purposes, the lumen means may have a narrowed distal endwhereby the catheter may be normally guided along a guidewire while theradioactive radiation means may be sufficiently thick for not passingthrough the narrowed distal end. Similarly the lumen means may be closeddistally.

The waist or belted balloon catheter may be adapted to several practicalconfigurations, for example to allow use of the technology known underthe trade mark MONORAIL. In this case, the lumen means may be closeddistally, and the catheter may further comprise a guidewire lumen withan entry and an exit distal of the balloon, which advantageously resultsin a two lumen catheter construction which will be easily centeredwithin the balloon by the belt means. The catheter may also comprise aguidewire lumen with an entry distal of the balloon and an exit proximalof the balloon, the three lumen catheter so achieved being alsocorrectly centered within the balloon by the belt means.

In sum, the present invention relates to a medical appliance for thetreatment of a portion of body vessel by ionizing radiation with acatheter, an inflatable elongate balloon distally surrounding thecatheter, and lumen means longitudinally extending through the catheterfor positioning a radioactive radiation emitter within the balloon. Awaist on said balloon essentially centers the catheter within theballoon. The belt means may create the waist, and may be regularlyspaced from one another over the length of the balloon or irregularlyspaced from one another over the length of the balloon. The belt meansmay be made of surgical thread, which may be tied with a knot. The beltmeans may be made of molded rings. The belt means may be affixed to theballoon, such as by adhesion. The lumen means may have a narrowed distalend, and may be closed distally. The catheter may further have aguidewire lumen with an entry and an exit distal of the balloon, or aguidewire lumen with an entry distal of the balloon and an exit proximalof the balloon.

In an alternative embodiment, the present invention relates to acatheter that may have an elongate tubular member having a distalportion with an outside diameter; an at least partially expandableballoon configured on the distal portion of the tubular member, theballoon having a distal end, a proximal end, and at least oneintermediate segment therebetween; and balloon expansion restrictionmeans for limiting the expansion of at least one intermediate segment sothat the segment does not substantially expand. The catheter may alsohave an elongate tubular member; and a balloon configured on the tubularmember, the balloon having a proximal segment, a distal segment and atleast one intermediate segment wherein the proximal and distal segmentsare inflatable to diameters which are greater than the inflatablediameters of the at least one intermediate segment. In anotherembodiment, the catheter may have an elongate tubular member having anoutside diameter; an at least partially expandable balloon configured onthe tubular member; a first zone on the balloon, inflatable to a firstinflated diameter; and a second zone on the balloon, inflatable to asecond diameter; wherein the second diameter is essentially the samediameter as the outer diameter of the tubular member.

DESCRIPTION OF THE DRAWINGS

These and other objects will become readily apparent from the followingdetailed description with reference to the accompanying drawings whichshow diagrammatically and by way of example only four embodiments of theinvention.

FIGS. 1 to 4 are respectively longitudinal cuts of the first, second,third and fourth embodiments.

In all the embodiments shown only the portions of the medical appliancewhich have to be located at the site of treatment have been depicted,the other portions of the embodiments being devised as currentlypracticed in the art. The portion of the body vessel where treatmentoccurs has not been shown.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The described materials are specifically directed to percutaneoustransluminal angioplasty. This is however not limitative and theinvention is also applicable to materials directed to the treatment ofother body vessels.

The first embodiment of FIG. 1 is a balloon catheter comprising acatheter tube 1 surrounded distally by an elongated inflatable balloon2. The balloon 2 is proximally and distally affixed, for instancewelded, to the catheter tube 1 as commonly practiced in the art.Throughout the catheter tube 1 is a longitudinal lumen 3 which isadapted to position a guidewire and/or a radioactive radiation emitterwithin the balloon 2. The catheter 1 comprises a second lumen 4 fordirecting inflation fluid into the balloon 2. The balloon 2 is shown ininflated condition at the location of a stenosis (not shown) of a bloodvessel such as a coronary artery. A radioactive radiation emitter 5, inthis example in the form of a coiled filament, is affixed to the distalend of a guidewire 6, and this coiled filament is sized for asubstantial sliding fit within the lumen 3 of catheter tube 1.

Two belt means 7 creating a waist, in this example molded ringsregularly spaced from one another over the length of the balloon, aremounted on the balloon 2 for essentially centering the catheter 1 withinthe balloon 2. The belt means 3 are affixed to the balloon 2, forexample adhesively adhered thereto, and they squeeze the balloon 2 downto nearly the diameter of the catheter thereby leaving a small passage 8for the inflation fluid supplied to the balloon 2 via lumen 4. The beltmeans 7 divide the balloon 2 into sections 9 which are substantiallysimilar and they assure a close center fit of the catheter 1 within theballoon 2 at least at the respective locations of the lace, therebyeliminating, or at least strongly minimizing, the effects of catheterwarping upon inflation of the balloon. The lumen 3 and radioactiveradiation emitter 5 in sliding fit therein are thus essentially centeredinside the vessel, at least at the locations of the lace.

The second embodiment of FIG. 2 is also a balloon catheter comprising acatheter tube 11 distally surrounded by an elongated inflatable balloon12 affixed to the catheter as usual in the art. Throughout the cathetertube 11 is a longitudinal lumen 13 adapted to position a guidewireand/or a radioactive radiation emitter within the balloon 12. At thedistal end of the catheter 11, the lumen 13 has a narrowed distal end 20the purpose of which of which is to allow passage of a guidewire whilepreventing passage of a radioactive radiation emitter which is made alittle thicker than the guidewire. The catheter comprises a second lumen14 for supplying inflation fluid to the balloon 12. A radioactiveemitter 15, also in the form of a coiled filament, is affixed to thedistal end of a guidewire 16, this coiled filament being sized for asubstantial sliding fit within the lumen 13 of catheter tube 11.

As for the embodiment of FIG. 1, two belt means 17 creating a waist areformed of molded rings which are regularly spaced from one another overthe length of the balloon and which are mounted on the balloon andadhesively adhered thereto for essentially centering the catheter 11within the balloon 12. These belt means 17 squeeze the balloon 12 downto nearly the diameter of the catheter in order to leave a small passage18 for the inflation fluid supplied to the balloon via lumen 14. Thebelt means 17 also divide the balloon 12 into sections 19 which aresubstantially similar, and they assure a close center fit of thecatheter 11 within the balloon 12 at least at the respective locationsof the lace to substantially eliminate the effects of catheter warpingupon inflation of the balloon, whereby the lumen 13 and radioactiveradiation emitter 15 in sliding fit therein will be essentially centeredinside the vessel, at least at the locations of lace.

The third embodiment of FIG. 3 is a balloon catheter which makes use ofthe MONORAIL (trade mark) catheter technology. This balloon cathetercomprises a catheter tube 31 distally surrounded by an elongated balloon32 affixed to the catheter tube. Within the catheter tube 31 is alongitudinal lumen 33 preferably distally closed at a location 40substantially corresponding to the distal end of balloon 32, which lumen33 is for allowing passage of a guiding wire 36 provided with a distalradioactive radiation emitter 35 the travel of which is limited forsafety purposes by the closed distal end 40 of lumen 33. The catheteralso comprises a lumen 34 for supplying inflation fluid to the balloon32. The catheter 31 further comprises a guidewire lumen 41 with an entry42 and exit 43 distal of the balloon 32 for accommodating a guidewire 44in the MONORAIL (trade mark) configuration.

As for the previous embodiments, a waist is created by two belt means 37which are formed of molded rings regularly spaced from one another overthe length of the balloon 32 and which are mounted on the balloon andadhesively secured thereto for essentially centering the catheter 31within the balloon 32. Belt means 37 squeeze the balloon 32 to nearlythe diameter of the catheter 31 and thereby leave a small passage 38 forthe inflation fluid ejected by lumen 34. Belt means 37 divide theballoon 32 into similar sections 39 and they assure a close center fitof catheter 31 within the balloon 32, at least at the respectivelocations of the lace. As in the previous embodiments, this structuresubstantially eliminates the effects of catheter warping upon inflationof the balloon and therefore the lumen 33 and radioactive radiationemitter 35 in sliding fit therein will be essentially centered in thebody vessel, at least at the locations of lace.

The fourth embodiment of FIG. 4 also makes use of the MONORAIL (trademark) technology. This balloon catheter comprises a catheter tube 51distally surrounded by an elongated balloon 52. Within catheter tube 51is a longitudinal lumen 53 for allowing passage of a guiding wire 56provided with a distal radioactive radiation emitter in the form of afilament 55 sized for a sliding fit into lumen 53. The catheter alsocomprises a lumen 54 for supplying inflation fluid to the balloon 53 anda guidewire lumen 60, preferably symmetrical to lumen 54 with respect tothe longitudinal axis of the catheter, having an entry 61 distal of theballoon 52 and an exit 62 proximal of the balloon 52 for accommodating aguidewire 63 in the MONORAIL (trade mark) configuration.

This embodiment also comprises a waist made of two belt means 57 formedof molded rings regularly spaced from one another over the length of theballoon 52 and adhesively secured on the balloon for essentiallycentering the catheter 51 within the balloon 52. Belt means 57 squeezethe balloon 52 to nearly the diameter of catheter 51 thereby leaving asmall passage 58 for the inflation fluid arising from lumen 54. Beltmeans 57 divide the balloon 52 in three similar sections 59, therebyassuring a close center fit of catheter 51 within the balloon at leastat the respective site of the lace, a structure which substantiallyeliminates the effects of catheter warping upon inflation of theballoon, despite the three lumen construction. The lumen 53 andradioactive radiation filament 55 in sliding fit therein will thereforebe essentially centered in the body vessel, at least at the locations oflace.

Variants may be envisaged.

For instance, the belt means may be made of surgical thread; they may bemade possibly of surgical thread tied with a knot.

The belt means may also be made of molded rings of different lengthand/or thickness.

The belt means may be irregularly spaced from one another over thelength of the balloon. Within this frame, it is possible to have arepartition of belt means providing a central section of the balloonwhich is longer than a proximal and a distal section thereof.

It is possible to have more than two belt means to constitute the waistin case of long balloon configurations as well as it is possible to haveonly one belt means forming a waist in case of relatively short balloonconfigurations.

The belt means may be simply squeezing the balloon, without beingaffixed thereto. They may also be affixed to the balloon by welding.

And of course, the radioactive radiation emitter may be of any shape,configuration or material, other than the coil or filament described.

We claim:
 1. A medical appliance for the treatment of a portion of abody vessel by ionizing radiation, comprising:a catheter; an inflatableelongated balloon distally disposed about the catheter, the catheterincluding a lumen longitudinally extending through at least a portion ofthe catheter proximate the balloon, the lumen having a size sufficientto receive a radioactive radiation emitter; and a waist on said balloonbetween the first and second longitudinal ends thereof and substantiallycentering the catheter within the balloon.
 2. A medical applianceaccording to claim 1, wherein the waist comprises a belt.
 3. A medicalappliance according to claim 2, and further comprising a plurality ofbelts regularly spaced from one another along the length of the balloon.4. A medical appliance according to claim 2, wherein the belt means areirregularly spaced from one another over the length of the balloon.
 5. Amedical appliance according to claim 1, wherein the belt means are madeof surgical thread.
 6. A medical appliance according to claim 5, whereinthe belt means are made of surgical thread tied with a knot.
 7. Amedical appliance according to claim 1, wherein the waist is made of amolded ring.
 8. A medical appliance according to claim 1, wherein thewaist is affixed to the balloon.
 9. A medical appliance according toclaim 8, wherein the waist is adhesively affixed to the balloon.
 10. Amedical appliance according to claim 1, wherein said lumen means have anarrowed distal end.
 11. A medical appliance according to claim 1,wherein said lumen means are closed distally.
 12. A medical applianceaccording to claim 1, wherein said catheter further comprises aguidewire lumen with an entry and an exit distal of the balloon.
 13. Amedical appliance according to claim 1, wherein said catheter furthercomprises a guidewire lumen with an entry distal of the balloon and anexit proximal of the balloon.
 14. A catheter comprising:(a) an elongatetubular member having a distal portion with an outside diameter; (b) anat least partially expandable balloon disposed on the distal portion ofthe tubular member, the balloon having a distal end, a proximal end, andat least one intermediate segment therebetween; and (c) at least oneballoon expansion restrictor coupled to the balloon, limiting theexpansion of at least one intermediate segment so that the segment doesnot substantially expand.
 15. A catheter comprising:an elongate tubularmember; and a balloon configured on the tubular member, the balloonhaving a proximal segment, a distal segment and at least oneintermediate segment wherein the proximal and distal segments areinflatable to diameters which are greater than the inflatable diametersof the at least one intermediate segment.
 16. A catheter comprising:anelongate tubular member having an outside diameter; an at leastpartially expandable balloon on the tubular member; a first zone on theballoon, inflatable to a first diameter; and a second zone on theballoon, inflatable to a second diameter; wherein the second diameter issubstantially the same diameter as the outside diameter of the tubularmember.